The present invention relates to an optical recording device for forming an indented pattern on a master magnetic recording tape.
A system for recording a video signal, an audio signal or the like on a magnetic recording medium and for playing it back, using a magnetic head, is widely adopted at present. However, this system is not satisfactory in consideration of low recording density and low S/N ratio.
On the other hand, video discs are recently developed wherein signals are recorded in an indented pattern using a laser beam or an electron beam and the recorded signals are reproduced mechanically, electrostatically, or optically. Such video discs are almost commercially available. An indented pattern in the order of submicrons can be easily formed in accordance with recent laser beam and electron beam techniques. A video disc of this type can perform recording/playback with high density and high S/N ratio. However, a special playback device is required for this video disc in order to reproduce the recorded signals. Such a playback device is very expensive as compared with currently used magnetic recording/playback devices.
In order to solve this problem with the conventional video disc, the present inventors proposed a system wherein signals are recorded in an indented pattern on a first magnetic recording medium and the recorded signals on the first magnetic recording medium are magnetically transferred to a second magnetic recording medium by bringing the first magnetic recording medium into contact with the second magnetic recording medium and by applying a magnetic field to the first and second magnetic recording media. According to this system, since the indented pattern corresponding to the signals recorded on the first magnetic recording medium can be formed in the order of submicrons, the signals transferred and recorded on the second magnetic recording medium are very high in recording density. Further, recording on the second magnetic recording medium is performed magnetically, so that playback can be, in principle, performed by conventional magnetic recording/playback device.
As a recording/playback device of a video signal, a helical scan type VTR is mostly used wherein the recording tracks (video tracks) for the video signal are inclined by a rotary head mechanism with respect to the longitudinal direction of the magnetic recording tape. Therefore, when the playback operation is to be performed using this helical scan type VTR, the signals which are transferred and recorded on the second magnetic recording tape as the second magnetic recording medium in accordance with the magnetic transfer recording system as described above must be recorded in an inclined recording track with respect to the longitudinal direction of the magnetic recording tape. For this purpose, the signals which are recorded in the indented pattern on the first magnetic recording tape as the first magnetic recording medium must be also recorded in a recording track inclined with respect to the second magnetic recording tape.
In the conventional VTR, an azimuth recording system is mostly adopted to further increase the recording density. According to this system, an inclined angle (azimuth) of an elongate magnetization pattern with respect to the longitudinal direction of a recording track differs from that of an adjacent recording track so as to reduce crosstalk between the recording tracks. Thus, a guard band between the recording tracks is eliminated to increase the recording density. Therefore, when adaptability of the present invention to a VTR with the azimuth recording system of this type is considered, for each recording track, the signals of the indented pattern must be recorded on the first magnetic tape at an azimuth different from an azimuth at which the signals are recorded on the second magnetic tape.